138 lines
3.8 KiB
C++
138 lines
3.8 KiB
C++
/* Copyright 2015 OpenMarket Ltd
|
|
*
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
|
* you may not use this file except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*/
|
|
#include "olm/cipher.hh"
|
|
#include "olm/crypto.hh"
|
|
#include "olm/memory.hh"
|
|
#include <cstring>
|
|
|
|
olm::Cipher::~Cipher() {
|
|
|
|
}
|
|
|
|
namespace {
|
|
|
|
struct DerivedKeys {
|
|
olm::Aes256Key aes_key;
|
|
std::uint8_t mac_key[olm::KEY_LENGTH];
|
|
olm::Aes256Iv aes_iv;
|
|
};
|
|
|
|
|
|
static void derive_keys(
|
|
std::uint8_t const * kdf_info, std::size_t kdf_info_length,
|
|
std::uint8_t const * key, std::size_t key_length,
|
|
DerivedKeys & keys
|
|
) {
|
|
std::uint8_t derived_secrets[2 * olm::KEY_LENGTH + olm::IV_LENGTH];
|
|
olm::hkdf_sha256(
|
|
key, key_length,
|
|
nullptr, 0,
|
|
kdf_info, kdf_info_length,
|
|
derived_secrets, sizeof(derived_secrets)
|
|
);
|
|
std::uint8_t const * pos = derived_secrets;
|
|
pos = olm::load_array(keys.aes_key.key, pos);
|
|
pos = olm::load_array(keys.mac_key, pos);
|
|
pos = olm::load_array(keys.aes_iv.iv, pos);
|
|
olm::unset(derived_secrets);
|
|
}
|
|
|
|
static const std::size_t MAC_LENGTH = 8;
|
|
|
|
} // namespace
|
|
|
|
|
|
olm::CipherAesSha256::CipherAesSha256(
|
|
std::uint8_t const * kdf_info, std::size_t kdf_info_length
|
|
) : kdf_info(kdf_info), kdf_info_length(kdf_info_length) {
|
|
|
|
}
|
|
|
|
|
|
std::size_t olm::CipherAesSha256::mac_length() const {
|
|
return MAC_LENGTH;
|
|
}
|
|
|
|
|
|
std::size_t olm::CipherAesSha256::encrypt_ciphertext_length(
|
|
std::size_t plaintext_length
|
|
) const {
|
|
return olm::aes_encrypt_cbc_length(plaintext_length);
|
|
}
|
|
|
|
|
|
std::size_t olm::CipherAesSha256::encrypt(
|
|
std::uint8_t const * key, std::size_t key_length,
|
|
std::uint8_t const * plaintext, std::size_t plaintext_length,
|
|
std::uint8_t * ciphertext, std::size_t ciphertext_length,
|
|
std::uint8_t * output, std::size_t output_length
|
|
) const {
|
|
if (encrypt_ciphertext_length(plaintext_length) < ciphertext_length) {
|
|
return std::size_t(-1);
|
|
}
|
|
struct DerivedKeys keys;
|
|
std::uint8_t mac[olm::SHA256_OUTPUT_LENGTH];
|
|
|
|
derive_keys(kdf_info, kdf_info_length, key, key_length, keys);
|
|
|
|
olm::aes_encrypt_cbc(
|
|
keys.aes_key, keys.aes_iv, plaintext, plaintext_length, ciphertext
|
|
);
|
|
|
|
olm::hmac_sha256(
|
|
keys.mac_key, olm::KEY_LENGTH, output, output_length - MAC_LENGTH, mac
|
|
);
|
|
|
|
std::memcpy(output + output_length - MAC_LENGTH, mac, MAC_LENGTH);
|
|
|
|
olm::unset(keys);
|
|
return output_length;
|
|
}
|
|
|
|
|
|
std::size_t olm::CipherAesSha256::decrypt_max_plaintext_length(
|
|
std::size_t ciphertext_length
|
|
) const {
|
|
return ciphertext_length;
|
|
}
|
|
|
|
std::size_t olm::CipherAesSha256::decrypt(
|
|
std::uint8_t const * key, std::size_t key_length,
|
|
std::uint8_t const * input, std::size_t input_length,
|
|
std::uint8_t const * ciphertext, std::size_t ciphertext_length,
|
|
std::uint8_t * plaintext, std::size_t max_plaintext_length
|
|
) const {
|
|
DerivedKeys keys;
|
|
std::uint8_t mac[olm::SHA256_OUTPUT_LENGTH];
|
|
|
|
derive_keys(kdf_info, kdf_info_length, key, key_length, keys);
|
|
|
|
olm::hmac_sha256(
|
|
keys.mac_key, olm::KEY_LENGTH, input, input_length - MAC_LENGTH, mac
|
|
);
|
|
|
|
std::uint8_t const * input_mac = input + input_length - MAC_LENGTH;
|
|
if (!olm::is_equal(input_mac, mac, MAC_LENGTH)) {
|
|
olm::unset(keys);
|
|
return std::size_t(-1);
|
|
}
|
|
|
|
std::size_t plaintext_length = olm::aes_decrypt_cbc(
|
|
keys.aes_key, keys.aes_iv, ciphertext, ciphertext_length, plaintext
|
|
);
|
|
|
|
olm::unset(keys);
|
|
return plaintext_length;
|
|
}
|